Load disconnect switch system for a wireless powered appliance

Abstract

A power circuit for resonant power transmission to an appliance that receives power through an electromagnetic transmission from a power transmitter. The power circuit uses a near field communication (NFC) to detect wireless communication to the appliance. A relay that selectively decouples a load when the appliance and the power transmitter are not in a connected state. A latching circuit is used to trigger the relay in a connected state. The relay is held close by a storage element that is powered from by an NFC circuit.

We claim: 
     
         1 . A power circuit with near field communication (NFC) using resonant power transmission to power an appliance, the power circuit comprising:
 a relay to selectively couple or decouple a load for the appliance;   an NFC circuit comprises a data communication circuit for receiving data;   a power supply harvesting the resonant power transmission to the appliance;   a latching circuit that controls the relay to couple the power supply to the load when the data communication circuit detects wireless communication to the appliance, wherein:
 the latching circuit decouples the power supply to the load if the appliance is disconnected, 
 the decoupling is delayed after disconnection, and 
 the delay is enabled with power from the NFC circuit. 
   
     
     
         2 . The power circuit with NFC using resonant power transmission to power the appliance of  claim 1 , wherein the relay decouples the load if the appliance does not follow a communication protocol. 
     
     
         3 . The power circuit with NFC using resonant power transmission to power the appliance of  claim 1 , wherein the delay is caused by a capacitor that charged through a resistor from a power harvested from the NFC circuit. 
     
     
         4 . The power circuit with NFC using resonant power transmission to power the appliance of  claim 1 , a power regulator provides lower voltage than the power supply wherein a resistor at an input of the power regulator discharges capacitance. 
     
     
         5 . The power circuit with NFC using resonant power transmission to power the appliance of  claim 1 , wherein the delay is caused by a storage element that holds closed the relay during a transition from a powered state to a connected state. 
     
     
         6 . The power circuit with NFC using resonant power transmission to power the appliance of  claim 1 , wherein the latching circuit can be an SCR switch controlled by a microcontroller unit. 
     
     
         7 . The power circuit with NFC using resonant power transmission to power the appliance of  claim 1 , wherein the latching circuit can be an S-R latch constructed from a plurality of complementary metal-oxide semiconductor (CMOS) gates and a small signal transistor. 
     
     
         8 . A method for power delivery using resonant power transmission to power an appliance utilizing near field communication (NFC), the method comprising:
 selectively decoupling a load for the appliance with a relay;   receiving data with a communication circuit in an NFC circuit;   detecting presence of a power transmitter;   in response to detecting a power transmitter, controlling the relay by a latching circuit and hold the relay close during the resonant power transmission, wherein decoupling is delayed as a function of a storage element; and   providing power by the storage element to the relay, wherein:
 the power is harvested from a resonant power transmission to the appliance, and 
 the storage element is energized with power from the NFC circuit. 
   
     
     
         9 . The method for power delivery using resonant power transmission to power the appliance utilizing NFC of  claim 8 , wherein the relay decouples the load if the appliance does not follow a communication protocol. 
     
     
         10 . The method for power delivery using resonant power transmission to power the appliance utilizing NFC of  claim 8 , wherein the storage element is a capacitor charged through a resistor from a power harvested from the NFC circuit. 
     
     
         11 . The method for power delivery using resonant power transmission to power the appliance utilizing NFC of  claim 8 , a power regulator provides lower voltage than the power wherein a bleeder element discharges the storage element with a plurality of resistors added at an input of the power regulator. 
     
     
         12 . The method for power delivery using resonant power transmission to power the appliance utilizing NFC of  claim 8 , wherein the latching circuit can be an SCR switch controlled by a microcontroller unit. 
     
     
         13 . The method for power delivery using resonant power transmission to power the appliance utilizing NFC of  claim 8 , wherein the latching circuit can be an S-R latch constructed from a plurality of complementary metal-oxide semiconductor (CMOS) gates and a small signal transistor. 
     
     
         14 . The method for power delivery using resonant power transmission to power the appliance utilizing NFC of  claim 8 , the communication circuit transmits data including a load impedance and a power level of the appliance. 
     
     
         15 . The method for power delivery using resonant power transmission to power the appliance utilizing NFC of  claim 8 , wherein the storage element that holds closed the relay during a transition of the appliance from a connected state to a powered state. 
     
     
         16 . A power circuit with near field communication (NFC) using resonant power transmission to power an appliance, comprises:
 a relay to selectively couple or decouple a load for the appliance;   an NFC circuit comprises a data communication circuit for receiving data;   a power supply harvesting the resonant power transmission to the appliance;   a latching circuit that controls the relay to couple the power supply to the load when the data communication circuit detects wireless communication to the appliance, wherein:
 the latching circuit decouples the power supply to the load if the appliance is disconnected, 
 the decoupling is delayed as a function of a storage element and a bleeder element, and 
 the storage element is energized with power from the NFC circuit. 
   
     
     
         17 . The power circuit with NFC using resonant power transmission to power the appliance of  claim 16 , wherein the relay decouples the load if the appliance does not follow a communication protocol. 
     
     
         18 . The power circuit with NFC using resonant power transmission to power the appliance of  claim 16 , wherein the storage element is a capacitor that is energized through a resistor from a power harvested from the NFC circuit. 
     
     
         19 . The power circuit with NFC using resonant power transmission to power the appliance of  claim 16 , a power regulator provides low voltage wherein the bleeder element is a plurality of resistors that is added at an input of the power regulator to discharge the storage element. 
     
     
         20 . The power circuit with NFC using resonant power transmission to power the appliance of  claim 16 , wherein the storage element closes and holds the relay during a transition from a powered state to a connected state.